Office for Nuclear Regulation

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Trawsfynydd Decommissioning Site – Level 1 Exercise

Executive summary

Purpose of intervention

The purpose of this intervention was to carry out a planned observation of the site’s Level 1 ‘demonstration’ exercise in accordance with the 2015/16 integrated intervention strategy (ISS) plan for the Trawsfynydd nuclear installation.

Interventions Carried Out by ONR

I, supported by two ONR colleagues, observed the Trawsfynydd Level 1 exercise ‘Spitfire’ on 19th May 2015.  We assessed the adequacy of the licensee’s emergency response to an agreed accident scenario and we also considered the suitability of the site’s emergency arrangements made under Licence Condition 11. Feedback was given to site staff before we left the site.

The scenario included a simulated dropped waste drum, a casualty that required medical assistance, contamination of individuals and location of missing persons.  On the day there was an added complication as the site’s electronic muster system genuinely failed and therefore accounting for people relied upon the slower manual muster process.  ONR inspectors put most of their resource into observing actions at the ECC, ACP and Security Lodge.  We also observed the team that rescued the casualty and the subsequent handover of the individual to the ambulance service staff that attended the site.

Following the exercise, at the debrief, the site confirmed that the electronic muster was operational again.  They reported that they felt that they had coped well with the scenario and they were open regarding identified areas for improvement.  The Magnox assurance team, that carried out its own independent exercise observations, raised many good points that they had seen and some areas for improvement; these were consistent with the ONR view.  I thanked everyone for their efforts during the exercise including the ambulance service for supporting the licensee and concluded that ONR had seen “an adequate demonstration of the site’s emergency arrangements”.

It was noted that as ONR had recently agreed that the site no longer requires an off-site plan under REPPIR, the site is working on a new emergency plan and there will be changes to the site’s emergency arrangements before the next planned Level 1 demonstration exercise.

Explanation of Judgement if Safety System Not Judged to be Adequate

N/A.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

Based upon their experience of witnessing many exercises, and being mindful of ONR guidance (ONR Guide; LC 11 – Emergency Arrangements; NS-INSP-GD-011 Revision 3; January 2015), the ONR observation team all agreed that the exercise had provided an adequate demonstration of the licensee’s emergency arrangements at the site and no significant concerns had arisen. 

Conclusion of Intervention

The ONR team was satisfied that should a real event occur then the site should cope and therefore no further intervention is needed in this area until the next formal demonstration exercise is planned.


Crynodeb gweithredol

Diben yr Ymyrraeth

Diben yr ymyrraeth hon oedd cyflawni gwaith arsylwi arfaethedig o ymarfer 'arddangos' Lefel 1 y safle yn unol â chynllun strategaeth ymyrraeth integredig (ISS) 2015/16 ar gyfer gosodiad niwclear Trawsfynydd.

Ymyraethau a Gyflawnwyd gan yr ONR

Fe arsylwais i, gyda chefnogaeth dau gydweithiwr o'r ONR, ymarfer Lefel 1 Trawsfynydd, ‘Spitfire’, ar 19 Mai 2015.  Fe asesom ddigonolrwydd ymateb argyfwng y trwyddedai i senario damweiniau a gytunwyd, ac fe ystyriom hefyd addasrwydd trefniadau argyfwng y safle a wnaed dan Amod Trwyddedu 11. Rhoddwyd adborth i staff y safle cyn i ni adael.

Roedd y senario yn cynnwys efelychiad o ollwng drwm gwastraff, anafedig oedd angen cymorth meddygol, halogi unigolion a lleoliad personau coll.  Ar y diwrnod cafwyd cymhlethdod ychwanegol oherwydd i system cynnull electronig y safle fethu'n wirioneddol ac felly roedd gwneud cyfrif o bobl yn dibynnu ar y broses gynnull â llaw arafach.  Rhoddodd arolygwyr yr ONR y rhan fwyaf o'u hadnoddau i mewn i arsylwi gweithredoedd yn yr ECC, ACP a'r Porthdy Diogelwch.  Arsylwom y tîm a achubodd yr anafedig a'r trosiant dilynol o'r unigolyn i staff y gwasanaeth ambiwlans a fynychodd y safle.

Yn dilyn yr ymarfer, yn y sesiwn ddilynol, cadarnhaodd y safle bod y system gynnull electronig yn weithredol eto.  Adroddont eu bod yn teimlo eu bod wedi ymdopi'n dda gyda'r senario a'u bod yn agored parthed meysydd a nodwyd ar gyfer gwelliant.  Cododd tîm sicrwydd Magnox, a gyflawnodd ei arsylwadau ymarfer annibynnol ei hun, nifer o bwyntiau da yr oeddynt wedi eu gweld a rhai meysydd ar gyfer gwelliant; roedd y rhain yn gyson â barn yr ONR.  Fe ddiolchais i bawb am eu hymdrechion yn ystod yr ymarfer, yn cynnwys y gwasanaeth ambiwlans am gefnogi'r trwyddedai, a chasglu bod yr ONR wedi gweld "arddangosiad digonol o drefniadau argyfwng y safle".

Nodwyd gan fod yr ONR wedi cytuno'n ddiweddar nad yw'r safle angen cynllun oddi ar y safle dan REPPIR bellach, bod y safle yn gweithio ar gynllun argyfwng newydd ac y bydd newidiadau i drefniadau argyfwng y safle cyn yr ymarfer arddangosiad Lefel 1 arfaethedig nesaf.

Esboniad o’r Dyfarniad os Nad oedd y System Ddiogelwch wedi cael ei Barnu yn Ddigonol.

Amherthnasol.

Casgliadau Allweddol, Barnau’r Arolygydd a Rhesymau dros Wneud Dyfarniadau

Yn seiliedig ar eu profiad o wylio nifer o ymarferion, ac wrth fod yn ystyrlon o ganllaw'r ONR (Canllaw ONR; LC 11 – Trefniadau Argyfwng; NS-INSP-GD-011 Adolygiad 3; Ionawr 2015), cytunodd pob aelod o dîm arsylwi'r ONR bod yr ymarfer wedi darparu arddangosiad digonol o drefniadau argyfwng y trwyddedai ar y safle ac na chodwyd unrhyw bryderon arwyddocaol. 

Casgliad yr Ymyrraeth

Roedd tîm yr ONR yn fodlon y byddai'r safle yn ymdopi mewn achos o ddigwyddiad gwirioneddol, ac felly nad oes angen ymyrraeth bellach yn y maes hwn tan y bydd yr ymarfer arddangos ffurfiol nesaf wedi ei drefnu.